Elements, Water, Carbohyrdates, Lipids and

Proteins

IB BIOLOGYTopics 3.1 & 3.2

Most common elements

C H O Ncarbon hydrogen oxygen nitrogen

Organic molecules contain both carbon and hydrogen

Other Important Elements and their Functions

Element Prokaryotes Plants Animals

Sulfur (S) Proteins Proteins proteins

Calcium (Ca) Flagella movement Forms cell plate during cytokinesis

Shells, bones and teeth

Phosphorus (P) Nucleic acids and ATP

Nucleic acids and ATP Nucleic acids and ATP

Iron (Fe) Cytochrome- used in respiration

Cytochrome- used in mitochondrial respiration

Haemoglobin; Cytochrome- used in mitochondrial respiration

Sodium (Na) Main ion in cytoplasm Transmission of nerve impulses

Water Polar molecule (has + and – ends)

O is slightly –; H is slightly +

Oxygen attracts electrons more strongly

Hydrogen Bonds

Hydrogen bonding- + and – ends of H2O attract each other (not a real bond, only an attraction force)

High specific heat- Polarity allows it to dissolve other polar molecules like sugars and amino acids, a ‘universal solvent’

Causes cohesion

Water properties- aquatic environment

Transparent: allows plants/algae to survive under water, other organisms to see in water.Ice floats, protecting the water below from freezing, allowing organisms to surviveCohesion allows for some organisms to ‘walk’ on water

Organisms and Water- Thermal PropertiesWater has a high specific heat, heat of fusion / heat of vaporization which allows it to store a lot of heat.

Value to organisms:can absorb larger amounts of energy and still remain liquid. Ex: large body of water have a constant temperaturecoolant effect = water absorbs large amounts of heat and cools the body (sweat)

Organisms and Water- coolant water requires high input of water to break the H

bonds to go from liquid to gas (high specific heat) Evaporation off the surface of organism allows it to

lose heat. Value to organism:

Desert plants increase transpiration when in danger of over-heating

Mammals sweat for thermo-regulation

Organisms and Water- metabolismGood for allowing metabolic reactionsWater is a good solvent due to polarityLiquid between the temperatures in most regions

of the EarthValue to organism:

Watery habitat dissolves substances that can be absorbed by organisms

Watery cytoplasm dissolves substances Easy for metabolic reactions to take place between

dissolved substances.

Organisms and Water- transport High specific heat

Heat transport- blood can transfer heat from hot regions of the body to cooler areas for thermoregulation.

Water is dense Allows it to support large particles like blood cells, fat and

transport by flowing Polarity

allows substances to be dissolved and therefore transported to all parts of organism.

Cohesion As water evaporates off of leaves, other water molecules are

pulled from below in the xylem of plants

Carbohydrates

Most abundant Short term energy storage

General molecular formula (CH2O)n

Basic unit: monosaccharides (fructose, glucose, galactose) Two monosaccharides: disaccharides (maltose, lactose, sucrose) Anything larger than this: polysaccharides (starch, glycogen, cellulose)

Monosaccharides

Glucose: one of main products of photosynthesis, starts cellular respiration - cell uses it as a source of energyGalactose: sugar in milk Fructose: sugar found in honey, fruits, vegetablesRibose/Deoxyribose: RNA/DNA structure

Disaccharides

Sucrose — common table sugar

(glucose + fructose)

Lactose — major sugar in milk

(glucose + galactose)

Maltose — product of starch digestion

(glucose + glucose)

PolysaccharidesStarches: plant storage (excess glucose)

Glycogen: animals storage (excess glucose).

-The liver and skeletal muscle are major deposits of glycogen.

Cellulose: plant structure (cell wall). Probably the single most abundant organic molecule in the biosphere. (fibers – paper, cotton)

Starch grains in potato cells

Cellulose fibers

Condensation/Hydrolysis

Condensation: 2 molecules are joined together + 1 water molecule produced

Hydrolysis: water helps break molecule into smaller units (monomers)

Lipids/FatsGlycerol + fatty acid chains

Large number of C - H bonds = non-polar molecules. Insoluble in water

Functions: -Long term energy storage-Thermal insulation (Arctic animals)-Major component of the cell membrane

The fatty "tail" is non-polar (Hydrophobic) The phosphate "head" is a polar (Hydrophilic)

phospholipid

FatsSaturated: full of hydrogens – solid at room temperature

Unsaturated: one or more double bonds connecting carbons – liquid at room temperature

FatsCis – Trans-Oil for frying causes some of the cis bonds to convert to trans bonds. Fatty acids with trans bonds are carcinogenic.

Cholesterol = fat-like substance; controls how fluid the cell membrane will

be necessary to produce vitamin D and

steroids (testosterone, estrogen, progesterone, cortisone…)

Energy contentAnimals use fats for energy storageFat stores lots of calories in a small space - 9Kca/g - against carbs (4Kcal/g)

ProteinsMade of amino acidsContain nitrogenMany functions:-Structural (muscles, collagen, keratin) -Enzymes (metabolism)-Carriers (hemoglobin, albumin)-Antibodies-Hormones (ex. insulin)-Membrane pumps (ATP pumps), receptors, neurotransmitters-Movement (actin, myosin)

Peptide Bondpeptide bond = joins two amino acids